Type II/Schottky heterojunctions-triggered multi-channels charge transfer in Pd-TiO₂-Cu₂O hybrid promotes...

Rapid charge recombination, limited light response, and slow surface reactions were observed in the photocatalysts, thereby limiting their future-oriented applications in photocatalytic hydrogen production through water splitting. Constructing a multi-channel charge separation photocatalysis system could solve those questions. In this study, Pd-TiO₂-Cu₂O composites were successfully accomplished via a facile chemical reduction method. The Pd-TiO₂-Cu₂O composite exhibited improved photocatalytic hydrogen production (13069.7 μmolg^-1h^-1), which was over 6 times as much as that of pure TiO₂. Based on the photo/electrochemical measurements, it was proposed that a Type II heterojunction was formed at the TiO₂-Cu₂O interface under light irradiation, and concurrently, a Schottky barrier was established between Pd and TiO₂. Accordingly, the Type II heterojunction-created built-in electric field would facilitate the separation of photogenerated charges. Simultaneously, the introduction of Pd accelerates the accumulation of electrons and further enhances the charge transfer rate. The combination of such a Type II heterojunction and Schottky junction synergistically created a multi-channel charge separation system, optimizing surface reactions and thus improving photocatalytic efficiency. This work provided a rational approach for building efficient multi-component photocatalysis systems featuring Type II heterojunction/Schottky junction for photocatalytic hydrogen evolution.